Performance of alkyd polyurethane coatings with hyperbranched alkyd
Hyperbranched alkyd was synthesised by single-step approach using trimethylolpropane, mono pentaerythritol as core material, and 2,2-bis(methylol)propionic acid (DMPA), a combination of dehydrated castor oil fatty acid and coconut oil fatty acid as chain extender.
Better performance with increase of chain entanglement
A series of hyperbranched alkyds was prepared at different degree of branching by changing the amount of DMPA in the resin formulation. The alkyds were converted into polyurethane coating after reaction with hexamethylene diisocyanate trimer in the presence of dibutyltin dilaurate as catalyst. The effect of branching and polymeric chain entanglement on the glass transition temperature Tg of the alkyd polyurethane coating (APUC) was studied. The performance of such APUC in terms of gloss, gloss retention under accelerated QUV radiation, natural outdoor exposed condition, mechanical and corrosion resistance properties was enhanced with the increase of polymeric chain entanglement, i.e., compactness or higher order of branching in the alkyd resin structure.
The study is published in: Applied Polymer Science, Volume 135, Issue 9, March 5, 2018.